1. Field of the Invention
The present invention relates to a thin film transistor (TFT) using an oxide semiconductor, a method of manufacturing the same, and a display unit including the same and an electronic device.
2. Description of the Related Art
In a flat panel display such as a liquid crystal display and an organic EL (electroluminescence) display, a silicon (Si) material is typically used as a channel layer (active layer) in a drive thin film transistor. Specifically, examples of the silicon material include an amorphous Si and a polycrystalline Si.
However, in the case where the amorphous Si is used as the channel layer, although it is possible to easily increase the size of the display, the mobility of a carrier (for example, an electron) is low as approximately 1 cm2/V·s, and it is thus difficult to realize high performance of the display. Meanwhile, in the case where the polycrystalline Si is used as the channel layer, although the mobility of the carrier is high as approximately 30 cm2/V·s to 300 cm2/V·s, variation of transistor characteristics is large in the plane, and it is thus difficult to increase the size of the display.
From these, development of a channel material having in-plane uniformity of the same level as the amorphous Si, and the carrier mobility of the same level as the polycrystalline Si is desired to realize both of an increase in size and high performance in the flat panel display.
Thus, an oxide semiconductor such as a zinc oxide, or an indium gallium zinc oxide (InGaZnO), in particular, amorphous InGaZnO4 or the like has been widely considered as a candidate of the channel material (for example, Japanese Unexamined Patent Publication No. 2007-281409).